The present invention relates to a finishing method for stepping motor stator stacks and rotor stacks, and more specifically to a finishing method for eliminating burrs, remaining on the small tooth surface of stator stacks and rotor stacks after abrasive finishing by means of a mechanical process, without loss of the original shape of the small teeth.
Stepping motor stators are formed by turning, stacking and laminating a plurality of magnetic steel plates formed with a plurality of magnetic pole parts at equal intervals oriented toward the central axis of the motor. Each of the plurality of magnetic pole parts in the steel plates has a plurality of small teeth formed at its tip at equal intervals in the direction of the circumference and oriented toward the central axis of the motor. Magnetic steel plates are laminated such that the plurality of small teeth have long, narrow protrusions and long, narrow grooves between adjacent protrusions.
In the process of forming or stamping a stator stack, typically accomplished by punching, a plurality of burrs and/or rough areas are created. Where a stator stack of this sort has only undergone an abrasive finishing by means of a mechanical process, these burrs or rough areas remain. Furthermore, after the plurality of magnetic steel plates have been turned, stacked and laminated, irregularities in the inside diameter are eliminated by means of stacking. However, processing burrs remain on the small tooth surfaces of each magnetic steel plate because of the honing process carried out to assure the roundness.
Conventional methods of eliminating these trimming burrs and processing burrs remaining on the small teeth of each of the laminated plates of the stator stack consisted of spraying beads from a blaster and brushing.
Unfortunately, these methods for removing burrs have multiple problems.
Specifically, using the method of spraying beads from a blaster it is difficult to uniformly eliminate the burrs remaining on the small tooth surfaces because of the orientation of the bead spray and the distance between the small teeth and the spray nozzle. Additionally, the removed burr dust and the beads fall into the spaces between the plural laminated steel plates and cannot easily be removed by cleaning. Subsequently, these removed burrs can cause poor rotation of the motor by lodging between the stator and the rotor.
Furthermore, in order to avoid a lack of uniformity during removal by brush abrasion using the brushing method, brushes must be moved back and forth in the direction of the small tooth stacks to remove the burrs. If the brush replacement frequency is not managed appropriately, removed burrs and abrasion dust from the brushes can lodge in the spaces between the plural laminated plates. Additionally, it is not easy to eliminate these particles through cleaning. Therefore, they can cause poor rotation of the motor by lodging between the stator and the rotor.
A stepping motor rotor stack is formed by laminating a plurality of round magnetic steel plates having a plurality of small teeth formed along the perimeter at equal intervals, the teeth being oriented toward the perimeter. By laminating a plurality of such magnetic steel plates, long, narrow protrusions are formed through the stacking, and long, narrow grooves are formed between adjacent protrusions.
Similarly to the stator stack, where a rotor stack has only undergone abrasive finishing by means of a mechanical process, burrs that arise in the process of punching for forming or stamping necessary shape in the magnetic steel plates remain in the finished product. Irregularities in an outer diameter of the rotor are typically eliminated in the process of lamination of the plurality of magnetic steel plates. However, processing burrs remain on the small tooth surfaces of each magnetic steel plate because of the grinding process carried out to assure the roundness.
Conventional methods of eliminating these trimming burrs and processing burrs remaining on the small teeth of each of the laminated plates of the rotor stack typically include spraying beads from a blaster, buffing and brushing.
Unfortunately, these methods for removing burrs have multiple problems.
More specifically and as mentioned above, the method of spraying beads from a blaster and the method of brushing have the same problems observed for these methods on stator stacks. Furthermore, when the buffing method is used, the components of the buffer become lodged in between the layers of the plural laminated steel plates and cannot be easily eliminated by cleaning. Subsequently, these removed burrs can cause poor rotation of the motor by lodging between the stator and the rotor. Even if elimination of these particles was possible, a great amount of time would be needed to do so.
As mentioned above, all of these conventional methods for eliminating trimming and processing burrs present problems. These burrs still remain on the small tooth surfaces of stepping motor stator stacks and rotor stacks that have been abrasively or finally finished by means of honing, grinding and other mechanical processes. Moreover, since all of these methods are ones where contact is made with the small teeth, difficulties arise in eliminating burrs without dulling these teeth. Other notable problems are having to suitably adjust and change the relative speed of rotation, the relative orientation of the motion of the jig, work-piece and adjusting the pressure used on the work-piece at the appropriate time. This results in difficulty in managing these working conditions and long processing time.